It looks like there is broken glass inside my wine bottle. What gives?

Ask Dr Vinny

Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions, from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics.

Dear Dr. Vinny,

I found what appear to be chunks of glass in a bottle of wine. There was no apparent breakage of the bottle itself, and my friend and I carefully inspected it once the glass pieces poured out. Could it have occurred during bottling?

—Amanda P.

Dear Amanda,

I haven’t inspected the chunks personally, but my guess is that it was something much less scary—tartrate crystals, which are harmless and a natural occurrence with wine. Sometimes they look like rock candy, sometimes they cling to a cork, and sometimes they look like shards of glass. Odorless and tasteless, they’re just crunchy crystals. I’ve heard them referred to as "wine diamonds," which is sweet and romantic. Who doesn’t want diamonds made of wine?

Tartaric acid is one of the acids found in wine grapes, and it tends to settle out of wine during fermentation and aging. It’s also sensitive to cold temperatures, and when a wine is chilled down, the tartaric acid can drop out of the wine and not dissolve again. Some wines actually go through a cold stabilization process to separate the tartrate crystals before the wines are bottled, purely for cosmetic reasons (and to make sure your wine isn’t crunchy).

If it helps, these crystals are also made from the same stuff that cream of tartar is (most cream of tartar is actually harvested from wine barrels). It’s what keeps my snickerdoodle cookies nice and airy.

—Dr. Vinny

Ask Dr. Vinny

More In Dr. Vinny

Should I refill my own wineglass, or ask the host or server to?

Wine Spectator's expert Dr. Vinny explains the etiquette or wine service, for hosts and for …

May 23, 2022

What’s the best way to remove the cork from an imperial (a 6-liter bottle of wine)?

Wine Spectator's expert Dr. Vinny explains best practices for opening—and serving—large-for…

May 16, 2022

Are wine tasting note descriptors listed in order of prominence?

Wine Spectator's resident wine expert Dr. Vinny explains that wine tasting notes are not …

May 9, 2022

How can a wine taster distinguish between so many different types of "pepper" in a wine?

Wine Spectator's resident wine expert Dr. Vinny explains where some pepper notes in wine …

May 2, 2022

Is it OK to bring a bottle of rosé to dinner at a restaurant?

Wine Spectator's expert Dr. Vinny explains corkage etiquette and BYO Dos and Don'ts

Apr 25, 2022

Why don't most 1.5-liter wine bottles have a vintage date?

Wine Spectator's expert Dr. Vinny explains why many wines are non-vintage, especially …

Apr 18, 2022